Cannot generate test for `export default` functions and classes

[tyuldashev]

Description
If function or class marked as export default then UTBot doesn't suggest to generate test for such objects.

To Reproduce

1. Install UnitTestBot plugin built from main in IntelliJ IDEA
2. Open some JavaScript project
3. Try to invoke Test Generation dialog for following code:

export default function cube(x) {
  return x * x * x;
}

Expected behavior
Dialog appears.

Actual behavior
When pressing hotkey, nothing happens. File context menu is disabled.

Screenshots, logs